JP2010047674A - Polyester imide precursor and polyester imide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester imide having high flame retardancy, a low hygroscopic expansion coefficient, a low linear heat expansion coefficient, a high glass transition temperature, a low elastic modulus and high tear strength and to provide a method for producing the same. <P>SOLUTION: This polyester imide precursor has recurring units represented by formula (1) and formula (2), and a molar ratio of formula (1) to formula (2) is 20/80 to 80/20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polyesterimide precursor and a polyesterimide used for a laminated board such as a flexible printed wiring board.

  Polyimide not only has excellent heat resistance, but also has characteristics such as chemical resistance, radiation resistance, electrical insulation, and excellent mechanical properties, so it is used for FPC (Flexible Printed Circuit) substrates and TAB (Tape Automated Bonding). Widely used in various electronic devices such as base materials, protective films for semiconductor elements, and interlayer insulating films for integrated circuits. In addition to these characteristics, polyimide has become increasingly important in recent years because of its simplicity of manufacturing method and extremely high film purity.

  As electronic devices become lighter, thinner, and more demanding, the demands on polyimide have become stricter year by year. Not only solder heat resistance, but also the dimensional stability of polyimide film against thermal cycling and moisture absorption, transparency, and adhesion to metal substrates There has been a demand for multifunctional polyimide materials that simultaneously satisfy a plurality of characteristics such as strength, moldability, and fine workability such as through holes.

  In recent years, the demand for polyimide as an FPC substrate has increased dramatically. The composition of the copper clad laminate and FCCL (Flexible Copper Clad Laminate), which are the raw materials of FPC, are mainly classified into three types. That is, 1) a three-layer type in which a polyimide layer (hereinafter also referred to as “polyimide film”) and a copper foil are attached using an epoxy adhesive, etc., 2) a polyimide solution is applied to the copper foil, and then dried or a polyimide precursor After applying the body solution, dry, imidize, or form a copper layer on the polyimide layer by vapor deposition / sputtering, etc. Non-adhesive two-layer type, 3) Pseudo two-layer type using thermoplastic polyimide as the adhesive layer, It has been known. In applications where a high degree of dimensional stability is required for the polyimide layer, a two-layer FCCL without an adhesive is advantageous.

  Polyimide as an FPC board undergoes dimensional changes when exposed to various thermal cycles in the mounting process. In order to suppress this as much as possible, in addition to the glass transition temperature (Tg) of the polyimide being higher than the process temperature, the coefficient of linear thermal expansion below the glass transition temperature is as low as possible, matching the coefficient of linear thermal expansion of the metal foil. It is desirable that As will be described later, the control of the linear thermal expansion coefficient of the polyimide layer is extremely important from the viewpoint of reducing the residual stress generated during the two-layer FCCL manufacturing process. In addition, for FPC boards, development of highly flame-retardant polyimide is desired from the viewpoint of safety.

  Many polyimides are insoluble in organic solvents and do not melt above the glass transition temperature, so it is usually not easy to mold the polyimide itself. Therefore, a polyimide is generally composed of an aromatic tetracarboxylic dianhydride such as pyromellitic anhydride (PMDA) and an aromatic diamine such as 4,4′-oxydianiline (ODA) and a dimethylacetamide (DMAc). First, a polyimide precursor solution having a high degree of polymerization is polymerized in an aprotic polar organic solvent, and this polyimide precursor solution is applied onto a metal foil, for example, a copper foil. The film is formed by heating and dehydration ring closure (imidization).

  Residual stress occurs in the process of cooling the metal / polyimide laminate to room temperature after the imidization reaction at high temperature, and serious problems such as FCCL curling, peeling, and film cracking often occur. Further, even when the polyimide solution is used, the problem of residual stress occurs in the drying-cooling process as in the case where the polyimide precursor solution is used.

  As a measure for reducing the residual stress, it is effective to reduce the coefficient of linear thermal expansion of polyimide itself as an insulating film. For most polyimides, the linear thermal expansion coefficient is in the range of 40 ppm / ° C. to 100 ppm / ° C., which is much larger than the linear thermal expansion coefficient of 17 ppm / ° C. of metal foils, for example, copper foils, which is close to the value of copper foil Research and development of a low linear thermal expansion polyimide that exhibits a linear thermal expansion coefficient of about 20 ppm / ° C. or less has been conducted.

  Currently, a polyimide formed from 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine is well known as a practical low linear thermal expansion polyimide material. This polyimide film shows a very low linear thermal expansion coefficient of 5 ppm / ° C. to 10 ppm / ° C., although it depends on the film thickness and production conditions, but does not show a low hygroscopic expansion coefficient (see Non-Patent Document 1).

  The dimensional stability of polyimide is required not only for thermal cycling but also for moisture absorption. Conventional polyimide absorbs 2% to 3% by weight of water. Circuit misalignment due to dimensional changes due to moisture absorption of the insulating layer is a serious problem for high-density wiring and multilayer wiring. A serious problem may be caused by deterioration of electrical characteristics such as corrosion at the polyimide / conductor interface, ion migration, and dielectric breakdown. Therefore, the polyimide layer as the insulating film is required to have a hygroscopic expansion coefficient as low as possible.

In order to realize a low hygroscopic expansion coefficient, for example, it has been reported that a polyesterimide using an acid anhydride having an ester structure in the skeleton represented by the formula (10) is effective (see Patent Document 1).

However, the polyesterimide film produced using the general formula (10) as the acid dianhydride and the formulas (11) to (13) as the diamine in order to realize a low hygroscopic expansion coefficient, the diamine has a highly flexible structure. Therefore, not only a high linear thermal expansion coefficient but also a polyesterimide film made of a combination thereof is considered to be a combustible film.

Here, when a diamine having a rigid structure such as formula (14) is used as the diamine, the coefficient of thermal expansion is low, but because of its rigidity, it has a high elastic modulus, which is not preferable in applications where low resilience is required. Further, it is presumed that the adhesion (peeling strength with the metal foil) is further lowered.

Therefore, a polyesterimide using an acid anhydride represented by the formula (15) has also been reported (see Patent Document 2).

In this case, there is a disclosure that a low coefficient of thermal expansion and a low water absorption (1.2% to 1.9%) can be achieved simultaneously. However, it is considered difficult for a polyesterimide film having a water absorption rate of 1.2% to satisfy a low hygroscopic expansion coefficient (8 ppm /% RH or less, 30% RH-70% RH). Moreover, in the processing process of the FPC board which consists of a thin film polyimide film, in order to avoid the fall of the yield by a polyimide film tear, it is calculated | required that a polyimide film is high tear strength, The said literature is about tear strength. Is not disclosed, and the disclosed polyesterimides cannot achieve high tear strength. Moreover, since the flexible molecule | numerator like Formula (11) and Formula (16) is used, it is thought that a glass transition temperature is also low.

  On the other hand, a polyesterimide using a compound having an ester structure as a diamine has also been reported (see Patent Document 3). However, in this case as well, it is considered that high tear strength cannot be obtained in the same manner as described above.

Thus, while maintaining the polymerization reactivity and film forming processability, it has the same low linear thermal expansion coefficient, high flame retardancy, and low hygroscopic expansion coefficient (8 ppm /% RH or less, 30% RH-70% RH) as copper foil. In addition to flexibility, solder heat resistance, high glass transition temperature, high adhesion, and low elastic modulus, it is not easy in terms of molecular design to obtain a polyimide that achieves high tear strength. At present, few practical materials are satisfactory to satisfy.
JP-A-10-70157 JP 2006-336011 A Japanese Patent No. 3712164 Macromolecules, 29, 7897 (1996).

  The present invention has been made in view of such points, and has high flame retardancy, low hygroscopic expansion coefficient, low linear thermal expansion coefficient equivalent to copper foil, high glass transition temperature, high adhesion, low elastic modulus, and high tear strength. And a polyesterimide having a low warpage and a precursor thereof.

（式（１）及び式（２）中、Ａｒは式（３）で表される４価の芳香族基である。式（２）中、Ｂは式（４）から式（８）の少なくとも１つより選択される２価の芳香族基であり、Ｒ_１〜Ｒ_９は炭素数１〜６のアルキル基、水素原子を表し、それぞれ独立であり、同じであっても異なっていてもよい。

The polyesterimide precursor of the present invention has repeating units represented by the following formula (1) and formula (2), and the molar ratio of formula (1) and formula (2) is formula (1) / formula (2 ) = 20/80 to 80/20.

(In the formulas (1) and (2), Ar is a tetravalent aromatic group represented by the formula (3). In the formula (2), B represents at least one of the formulas (4) to (8)). a divalent aromatic group selected from one, R ₁ to R ₉ is an alkyl group having 1 to 6 carbon atoms, represents a hydrogen atom, are each independently, may be different even in the same .

In the polyesterimide precursor of the present invention, in the polyesterimide precursor, B in Formula (2) is preferably a repeating unit represented by Formula (7), Formula (8), or Formula (9). And (7) is more preferable.

  In the polyesterimide precursor of the present invention, the weight average molecular weight Mw is preferably 30,000 to 400,000.

  The polyesterimide of the present invention is obtained by imidizing the polyesterimide precursor.

  The method for producing a polyesterimide of the present invention is characterized in that the polyesterimide precursor is heated or imidized using a dehydrating reagent to obtain a polyesterimide.

  The laminated board of this invention has a polyesterimide layer and a metal layer, and this polyesterimide layer is comprised from the said polyesterimide.

  The flexible printed wiring board of the present invention is characterized in that the metal layer of the laminated board is patterned into wiring.

  The polyesterimide obtained from the polyesterimide precursor according to the present invention has high flame retardancy, low hygroscopic expansion coefficient, low linear thermal expansion coefficient equivalent to copper foil, high glass transition temperature, high adhesion, low elastic modulus, high tearing. It has the effect of having both strength and low warpage.

  As a molecular design for low linear thermal expansion of polyimide, it is necessary to make the main chain skeleton as straight and rigid as possible (various conformations are difficult to take due to internal rotation). However, on the other hand, this reduces the entanglement of the polymer chains and may cause the film to become brittle. In addition, excessive introduction of a flexible unit such as an ether structure into the polyimide skeleton greatly contributes to improvement in film toughness and adhesion strength with metal foil, but it hinders the expression of low linear thermal expansion characteristics. is expected.

  The ester structure focused on in the present invention has a higher internal rotation barrier than the ether structure, and the change in conformation is relatively hindered. Therefore, the ester structure behaves as a rigid structural unit and imparts some flexibility to the polyimide main chain. It is expected to give a flexible film.

  In addition, since the ester structure has a lower polarizability than the amide structure or the imide structure, the introduction of the ester structure into the polyimide is advantageous for reducing the hygroscopic expansion coefficient.

Therefore, the polyesterimide precursor according to the present invention contains repeating units represented by the formulas (1) and (2), and the molar ratio of the formulas (1) and (2) is expressed by the formula (1). / Equation (2) = 20/80 to 80/20 ratio, high flame retardancy, low hygroscopic expansion coefficient, low thermal expansion coefficient equivalent to copper foil, high glass transition temperature, high adhesion, low The elastic modulus and high tear strength were realized at the same time. In Formula (1) and Formula (2), Ar is a tetravalent aromatic group represented by Formula (3). In formula (2), B is a divalent aromatic group selected from at least one of formulas (4) to (8), and R _{1 to} R ₉ are alkyl groups having 1 to 6 carbon atoms, hydrogen Represents an atom and each is independent and may be the same or different.

  The polyesterimide precursor according to the present invention is produced by using a monomer having an ester group-containing acid dianhydride and an ester group-containing diamine. Depending on the reaction position of the diamine and acid dianhydride, four types of isomers can be considered. Since the same product is obtained from the four types of isomers after imidation, the resulting polyesterimide precursor is represented by the general formula (1 ) And general formula (2).

When polymerizing the polyesterimide precursor of the present invention, tetracarboxylic dianhydride (TABP) having an ester structure represented by the formula (15) as a monomer having an ester group and an ester structure represented by the formula (17) A diamine (BPIP) having a diamine of formula (18) to formula (22) and formula (18) wherein R _{1 to} R ₃ are selected from the formula (23) selected from hydrogen atoms At least one of them is used. R _{1 to} R ₉ represent an alkyl group having 1 to 6 carbon atoms and a hydrogen atom, and are independent and may be the same or different. Here, from the viewpoint of the warp of the laminated board after curing and the tear strength of the resulting polyesterimide film, the formula (21), the formula (22), and the formula (23) are preferable, and the formula (21) is more preferable. In general, it is known that a polyesterimide film having a linear thermal expansion coefficient equivalent to that of copper foil is less warped after curing. The knowledge that it cannot be determined has been obtained, and the one having a linear thermal expansion coefficient equivalent to that of the copper foil and less warping is more preferable in the processing step of the FPC board.

  Here, in order to obtain a molar ratio of the formula (1) / formula (2) = 20/80 to 80/20, the tetracarboxylic dianhydride having an ester structure represented by the formula (15) and When all diamines are mixed at a ratio of about 1: 1 and the total diamines are 100 mol%, a diamine having an ester structure represented by the formula (17) is used at a diamine molar ratio of 20 mol% to 80 mol%, and the formula ( 18) to at least one diamine having an ester structure selected from the formula (22) is used at a diamine molar ratio of 20 mol% to 80 mol%.

  Here, from the viewpoint of the linear thermal expansion coefficient, the warp of the laminated plate after curing, and the tear strength of the resulting film, the molar ratio is a ratio of formula (1) / formula (2) = 20/80 to 80/20. It is preferable that the ratio is formula (1) / formula (2) = 30/70 to 70/30.

  Also, a polyimide having the above characteristics can be produced at low cost without using an expensive monomer such as a fluorinated monomer in order to obtain a low hygroscopic expansion coefficient.

  Embodiments of the present invention will be described in detail below, but these are examples of the embodiments of the present invention and the present invention is not limited to these contents.

  In the present invention, in addition to the structural characteristics such as rigidity and hydrophobicity of a monomer having an ester structure and a specific aromatic structure, an appropriate flexibility is blended in a balanced manner. High flame retardancy, low hygroscopic expansion coefficient, low linear thermal expansion coefficient equivalent to copper foil, high glass transition temperature, flexibility, high adhesion, low elastic modulus when used as an imide laminate and polyesterimide film In addition, it is possible to obtain a material having physical properties that cannot be obtained by a conventional material and has both high tear strength.

<Method for producing polyesterimide precursor>
The method for producing the polyesterimide precursor according to the present invention is not particularly limited, and a known method can be applied. More specifically, it is obtained by the following method.

  First, a diamine is dissolved in a polymerization solvent, tetracarboxylic dianhydride powder is gradually added thereto, and then a mechanical stirrer is used at 0 to 100 ° C., preferably 20 to 90 ° C. for 0.5 to 100 hours. Preferably, stirring is performed for 1 hour to 24 hours. In this case, the monomer concentration is preferably 5% by mass to 50% by mass, and more preferably 10% by mass to 40% by mass from the viewpoint of the degree of polymerization and the solubility of the monomer and the polymer to be formed. By carrying out polymerization in this monomer concentration range, a polyesterimide precursor solution having a uniform and high degree of polymerization can be obtained. Here, the obtained polyesterimide precursor solution is the same as the polyesterimide precursor described in the claims.

  In the present invention, tetracarboxylic dianhydride (hereinafter referred to as TABP) having an ester structure represented by the formula (15) is used. Here, this TABP is preferably highly pure from the viewpoint of making a high molecular weight polyimide precursor solution having no gel component, the adhesive strength of the metal / polyimide laminate, and the tear strength of the polyimide film. Specifically, in the profile shown by the differential scanning calorimeter, the peak temperature of the heat of fusion is (a) ° C., the virtual tangent line with the temperature at which the rise to the heat of fusion peak starts and the melting heat peak When the temperature at the intersection with the straight line along the substantially straight line portion is (b) ° C. and the temperature range ΔT = ((b) − (a)) ° C., (a) ≧ 322 ° C. and ΔT ≦ 5 ° C. It is preferable that the TABP satisfies the above. Furthermore, TABP satisfying (a) ≧ 325 ° C. and ΔT ≦ 4 ° C. is more preferable.

  The weight average molecular weight (Mw) of the polyesterimide film is preferably 30,000 to 400,000, and more preferably 30,000 to 300,000. Particularly preferred is 50,000 to 200,000. Here, from the viewpoint of toughness, 30,000 or more is preferable, and 50,000 or more is more preferable. Further, from the viewpoint of adhesiveness and coating property, the weight average molecular weight (Mw) is preferably 400,000 or less, more preferably 300,000 or less, and particularly preferably 200,000 or less.

  An aromatic tetracarboxylic dianhydride that can be used in combination with an acid dianhydride having an ester structure represented by the above formula (15) within a range that does not impair the required characteristics of the polyesterimide film and the polymerization reactivity of the polyesterimide precursor. As 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4 , 4′-Benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride, p-phenylenebis (trimellitic acid monoester anhydride), p-methylphenylene Bis (trimellitic acid monoester anhydride), 3,3 ′, 4,4′-biphenylsulfonetetracarboxylic dianhydride, 2,2′-bis (3,4) Dicarboxyphenyl) hexafluoropropanoic acid dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) propanoic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, etc. Can be mentioned. Two or more of these may be used in combination.

  Aliphatic tetracarboxylic dianhydride that can be used in combination with an acid dianhydride having an ester structure represented by the general formula (15) within a range that does not impair the required characteristics of the polyesterimide film and the polymerization reactivity of the polyesterimide precursor Although not particularly limited, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5- (dioxotetrahydrofuryl-3-methyl-3) -Cyclohexene-1,2-dicarboxylic anhydride, 4- (2,5-dioxotetrahydrofuran-3-yl) -tetralin-1,2-dicarboxylic anhydride, tetrahydrofuran-2,3,4,5-tetra Carboxylic dianhydride, bicyclo-3,3 ′, 4,4′-tetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1 Such as 2,3,4-cyclopentane tetracarboxylic acid dianhydride. It is also possible to use two or more of these.

  The polyester imide precursor according to the present invention has an ester structure represented by the general formula (17) and the general formula (18) to the general formula (23) as long as the required properties of the polyesterimide are not significantly impaired. Although it does not specifically limit as aromatic diamine which can be used together with diamine, p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 2,5-diaminotoluene, 2,4-diaminoxylene, 2,4- Diaminodurene, 4,4'-diaminodiphenylmethane, 4,4'-methylenebis (2-methylaniline), 4,4'-methylenebis (2-ethylaniline), 4,4'-methylenebis (2,6-dimethylaniline) ), 4,4′-methylenebis (2,6-diethylaniline), 4,4′-diaminodiphenyl ether, 3 4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 2,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminobenzophenone, 3, 3'-diaminobenzophenone, 4,4'-diaminobenzanilide, benzidine, 3,3'-dihydroxybenzidine, 3,3'-dimethoxybenzidine, o-tolidine, m-tolidine, 2,2'-bis (trifluoro Methyl) benzidine, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 4,4′-bis ( 4-Aminophenoxy) biphenyl, bis (4- (3-aminophenoxy) Enyl) sulfone, bis (4- (4-aminophenoxy) phenyl) sulfone, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 2,2-bis (4- (4-aminophenoxy) Phenyl) hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, p-terphenylenediamine and the like. Two or more of these may be used in combination.

  The polyester imide precursor according to the present invention has an ester structure represented by the general formula (17) and the general formula (18) to the general formula (23) as long as the required properties of the polyesterimide are not significantly impaired. Although it does not specifically limit as aliphatic diamine which can be used together with diamine, For example, 4,4'- methylenebis (cyclohexylamine), isophorone diamine, trans-1,4-diaminocyclohexane, cis-1,4-diaminocyclohexane, 1 , 4-cyclohexanebis (methylamine), 2,5-bis (aminomethyl) bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) bicyclo [2.2.1] heptane, 3, 8-bis (aminomethyl) tricyclo [5.2.1.0] decane, 1,3-diaminoadamantane, 2,2-bi (4-aminocyclohexyl) propane, 2,2-bis (4-aminocyclohexyl) hexafluoropropane, 1,3-propanediamine, 1,4-tetramethylenediamine, 1,5-pentamethylenediamine, 1,6- Examples include hexamethylene diamine, 1,7-heptamethylene diamine, 1,8-octamethylene diamine, and 1,9-nonamethylene diamine. Two or more of these may be used in combination.

  The solvent used in the polymerization reaction is not a problem as long as the raw material monomer and the produced polyesterimide precursor are dissolved, and the structure is not particularly limited. Specifically, amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε -Cyclic ester solvents such as caprolactone, α-methyl-γ-butyrolactone, carbonate solvents such as ethylene carbonate and propylene carbonate, glycol solvents such as triethylene glycol, m-cresol, p-cresol, 3-chlorophenol, 4- Examples thereof include phenol solvents such as chlorophenol, acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethyl sulfoxide and the like. From the viewpoint of solubility, aprotic solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, and 1,3-dimethyl-2-imidazolidinone are preferable. .

  In addition, other common organic solvents such as phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, tetrahydrofuran , Dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, terpene, mineral spirit, petroleum naphtha solvents, etc. Can also be used.

  The polyesterimide precursor according to the present invention can be isolated as a powder by dropping, filtering, and drying the polymerization solution into a large amount of poor solvent such as water or methanol.

<Method for producing polyesterimide>
The polyesterimide according to the present invention can be produced by subjecting the polyesterimide precursor obtained by the above method to a dehydration ring-closing reaction (imidation reaction). At this time, usable forms of polyesterimide are a film, a metal foil / polyesterimide laminate, a powder, a molded product, and a solution.

  A method for producing a polyesterimide film will be described. The polyesterimide precursor solution is cast onto a metal foil such as a copper foil or an aluminum foil and dried in an oven at 40 ° C. to 180 ° C., preferably 50 ° C. to 150 ° C. The obtained metal / polyesterimide precursor laminate was fixed on a SUS metal plate with tape, and in a vacuum, in an inert gas such as nitrogen, or in air, 200 ° C. to 430 ° C., preferably 250 ° C. A metal / polyimide laminate is obtained by heating at ~ 400 ° C. The polyesterimide film according to the present invention can be produced by etching and removing the metal layer of the laminate. There is also a method of obtaining a polyesterimide film using a silicon substrate on which a metal is deposited. In this case, the polyesterimide precursor solution is cast on a silicon substrate on which a metal layer is deposited, dried and heated by the above method, and a silicon / polyesterimide layer laminate on which the metal layer is deposited is obtained. . Thereafter, the metal layer of the laminate is etched and the polyesterimide layer (polyesterimide film) is peeled off from the silicon substrate, whereby the target product can be obtained.

  Furthermore, there is also a method for obtaining a polyesterimide film using a glass substrate. The polyester imide precursor solution is cast on a glass substrate and dried in an oven at 40 ° C. to 180 ° C., preferably 50 ° C. to 150 ° C., to obtain a glass substrate / polyesterimide precursor layer laminate. Thereafter, the polyesterimide precursor layer (polyesterimide precursor film) is peeled off from the laminate, the polyesterimide precursor film is fixed to a metal frame using a tape, and heated by the above-described method. Can be obtained.

  200 degreeC or more is preferable from a viewpoint of the ring closure reaction of imidation, and 430 degreeC or less is preferable from a viewpoint of the thermal stability of the produced | generated polyesterimide film. The imidization is desirably performed in a vacuum or in an inert gas, but may be performed in air if the imidization temperature is not too high.

  In addition, the imidization reaction is carried out by adding a tertiary amine such as pyridine or triethylamine to the polyesterimide precursor solution instead of heat treatment to produce a polyesterimide precursor film, and heating the chemical imide while heating at 200 ° C to 300 ° C. It is also possible to carry out by immersing the polyesterimide precursor film in a solution containing a dehydrating reagent such as acetic anhydride in the presence of a tertiary amine such as pyridine or triethylamine.

  Here, although the manufacturing method of the polyesterimide film from the polyesterimide precursor solution was described, it is not limited to this, The heat-dried polyesterimide precursor film and the isolated polyesterimide precursor are heated, Alternatively, a polyesterimide may be produced by cyclization using a dehydrating reagent. When the polyesterimide is insoluble in a solvent, a crystalline polyesterimide powder can be obtained as a precipitate. A molded body of polyesterimide can be produced by heating and compressing the polyesterimide powder at 200 ° C to 450 ° C, preferably 250 ° C to 430 ° C.

  Further, by adding and stirring a dehydrating reagent such as N, N-dicyclohexylcarbodiimide or trifluoroacetic anhydride in the polyesterimide precursor solution, the reaction is performed at 0 ° C to 100 ° C, preferably 0 ° C to 60 ° C. Polyisoimide, which is an isomer of polyesterimide, is formed. After forming a polyisoimide solution in the same procedure as described above, it can be easily converted to a polyesterimide by heat treatment at 250 ° C. to 450 ° C., preferably 270 ° C. to 400 ° C. The isoimidization reaction can also be performed by immersing the polyesterimide precursor film in a solution containing the dehydrating reagent.

  When the polyesterimide is dissolved in a solvent, the polyesterimide solution can be easily produced by heating the polyesterimide precursor solution as it is or after appropriately diluting with the same solvent to 150 ° C to 200 ° C. At this time, toluene, xylene, or the like may be added in order to azeotropically distill off water which is a by-product of imidization. Further, a base such as γ-picoline can be added as a catalyst.

  The obtained polyesterimide solution can be dropped and filtered in a large amount of poor solvent such as water or methanol to isolate the polyesterimide as a powder. The polyesterimide powder can be redissolved in the polymerization solvent to form a polyesterimide solution.

  The polyesterimide film can also be formed by applying the polyesterimide solution on a substrate and drying at 40 ° C to 400 ° C, preferably 100 ° C to 300 ° C.

  A polyester imide precursor solution is applied onto a metal foil, for example, a copper foil, dried, and then imidized under the above-described conditions, whereby a metal plate and a polyester imide layer laminate (FCCL) which is an original fabric of an FPC board are obtained. Obtainable. Here, a copper foil is used as the metal foil, and a non-adhesive two-layer type composed of a copper foil and a polyesterimide layer can be obtained by directly applying a polyesterimide precursor solution. On the other hand, a three-layer and pseudo two-layer type in which a polyesterimide layer and a copper foil are bonded using an epoxy adhesive or a thermoplastic polyimide as an adhesive are also generally known as FCCL configurations. In this case, since it is essential for the adhesive to be thermoplastic, it is essential to contain a bending component in the constituent unit of the adhesive, and the high hygroscopic expansion coefficient, glass transition temperature, and heat resistance are lowered. For this reason, in a three-layer or pseudo-two-layer type laminate, a high hygroscopic expansion coefficient, a low glass transition temperature, and a low heat resistance are inevitably caused by the thermoplastic adhesive layer. On the other hand, since the polyesterimide of the present invention has high adhesiveness, it is possible to obtain a two-layer laminate without using an adhesive layer, and the polyesterimide itself is also non-thermoplastic. Therefore, it is possible to simultaneously have high glass transition temperature heat resistance and low hygroscopic expansion coefficient.

  A polyester imide precursor solution is applied onto a metal foil, for example, a copper foil, dried, and then imidized under the above-described conditions, whereby a metal plate and a polyester imide layer laminate (FCCL) which is an original fabric of an FPC board are obtained. Obtainable.

  Various metal foils can be used as the metal foil of the FPC board, but aluminum foil, copper foil, and stainless steel foil are preferable, and copper foil is particularly preferable. . These metal foils may be subjected to surface treatment such as mat treatment, plating treatment, chromate treatment, aluminum alcoholate treatment, aluminum chelate treatment, silane coupling agent treatment, and the like.

  Although the thickness of metal foil is not specifically limited, Preferably it is 35 micrometers or less, More preferably, it is 18 micrometers or less.

FCCL can be manufactured as follows, for example.
First, the polyesterimide precursor solution is coated on a metal foil using a blade coater, a lip coater, a gravure coater or the like. Then, it is dried to form a polyesterimide precursor layer (hereinafter also referred to as “polyesterimide precursor film”). The coating thickness is affected by the solid content concentration of the polyesterimide precursor solution, but the polyesterimide precursor layer is heated at 200 ° C. to 400 ° C. in an inert atmosphere such as nitrogen, helium or argon. A polyesterimide layer can be formed by making it. The thickness of the polyesterimide layer is 100 μm or less, preferably 50 μm or less, more preferably 30 μm or less.

  Here, the peel strength from the metal foil is preferably 0.8 N / mm or more, and more preferably 1.0 N / mm or more. Warpage is preferably 10 mm or less, and more preferably 3 mm or less.

  By using the above FCCL as an etching solution using ferric chloride aqueous solution (manufactured by Tsurumi Soda Co., Ltd., 40 Baume, ferric chloride 37% or more) at room temperature or under 50 ° C. heating condition, By etching the metal layer into a desired circuit shape, an adhesive-free flexible printed wiring board can be manufactured.

  Here, the tear strength of the polyimide film is preferably 50 mN or more, more preferably 60 mN or more, and particularly preferably 80 mN or more in the polyimide film 26 μm. The elastic modulus is preferably 4.0 GPa to 6.5 GPa. The hygroscopic expansion coefficient is preferably 7 ppm /% RH or less, the linear thermal expansion coefficient is preferably 16 ppm / ° C. to 25 ppm / ° C., and the glass transition temperature is preferably 350 ° C. or higher.

  Add additives such as an oxidation stabilizer, a filler, an adhesion promoter, a silane coupling agent, a photosensitizer, a photopolymerization initiator, and a sensitizer to the polyesterimide of the present invention and its precursor solution as necessary. Can do.

  The polyesterimide of the present invention has high flame retardancy, low hygroscopic expansion coefficient, low linear thermal expansion coefficient equivalent to copper foil, high glass transition temperature, high adhesive strength, low elastic modulus, and high tear strength. It can be used for an electrical insulating film, a flexible printed wiring board, a display substrate, an electronic paper substrate, a solar cell substrate, etc. in a device, and is particularly useful as a substrate for a flexible printed wiring board.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, it is not limited to these Examples. In addition, the physical-property value in the following examples was measured by the method shown below.

<Polyesterimide precursor solution>
First, a diamine containing an ester structure is dissolved in N-methyl-2-pyrrolidone, tetracarboxylic dianhydride powder containing an ester structure is gradually added thereto, and heated at 80 ° C. using a mechanical stirrer. At 3 to 5 hours. At this time, the monomer concentration was polymerized in a monomer concentration range of 10% by mass to 20% by mass to obtain a polyesterimide precursor solution having a uniform and high polymerization degree.

<Copper foil / polyesterimide laminate>
A 12 μm-thick copper foil (NIPPON ELECTRIC CO., LTD. USLP foil) was placed on a metal coating table so that the matte surface was the surface. The surface temperature of the coating table was set to 90 ° C., and the polyesterimide precursor solution obtained above was applied to the copper foil mat surface with a doctor blade. Then, after leaving still for 30 minutes on a coating table, and further leaving still in a dryer at 100 ° C. for 30 minutes, a copper foil / polyesterimide precursor laminate without tackiness (polyesterimide precursor layer thickness 47 μm and 24 μm) was obtained. Next, a copper foil / polyesterimide precursor laminate was fixed on a SUS metal plate with a tape and fixed at 30 ° C. at 150 ° C. at a temperature rising rate of 5 ° C./min in a hot air drier in a nitrogen atmosphere. Min, imidization was carried out at 200 ° C. for 1 hour and at 400 ° C. for 1 hour. Then, the metal plate made from SUS was removed, and the laminated board of copper foil / polyesterimide was obtained.

<Polyesterimide film>
The copper foil of the copper foil / polyesterimide laminate obtained above was heated to a ferric chloride solution (Tsurumi Soda Co., Ltd., 40 Baume, ferric chloride 37% or more) at room temperature or 50 ° C. or less. By etching under, polyester imide films with film thicknesses of 26 μm and 12 μm were obtained.

<Weight average molecular weight: Mw>
0.01 g of a polyesterimide precursor solution was measured with a precision balance and dissolved in 10 g of a developing solvent. The developing solvent is 2.61 g of lithium bromide (Aldrich), 1 L of dimethylformamide (Wako Pure Chemical Industries, for liquid chromatography), phosphoric acid aqueous solution (Wako Pure Chemical Industries, purity 85%) 5 .88 g was dissolved. This solution was filtered through a 10 μm filter. Then, TPC guard Column Super H-H (trade name, manufactured by Tosoh Corporation) is used as a guard column, and TSK-GEL SUPER HM-H (trade name: manufactured by Tosoh Corporation) is connected in series as a preparative column. The molecular weight was measured at a flow rate of 0.5 ml / min using the above developing solvent. The molecular weight was converted using polystyrene.

<Glass transition temperature: Tg>
By using a thermomechanical analyzer (TMA-50) manufactured by Shimadzu Corporation, a polyesterimide film having a width of 3 mm, a length of 18 mm (length between chucks of 15 mm), and a thickness of 26 μm was measured by thermomechanical analysis. Measure the elongation at 50 ° C to 450 ° C under a nitrogen atmosphere (flow rate 20 ml / min) under a nitrogen atmosphere (flow rate 20 ml / min), and determine the glass transition temperature of the polyesterimide film (26 µm thickness) from the inflection point of the obtained curve. Asked.

<Linear thermal expansion coefficient: CTE>
By using a thermomechanical analyzer (TMA-50) manufactured by Shimadzu Corporation, a polyesterimide film having a width of 3 mm, a length of 18 mm (length between chucks of 15 mm), and a thickness of 26 μm was measured by thermomechanical analysis. Measure the elongation in the range of 50 ° C to 450 ° C under a nitrogen atmosphere (flow rate 20 ml / min) under a nitrogen atmosphere (flow rate 20 ml / min). As the average value of the film elongation in the range of 50 ° C to 200 ° C, ) Was determined.

<Hygroscopic expansion coefficient: CHE>
A polyester imide film having a width of 3 mm, a length of 30 mm (a length between chucks of 15 mm), and a thickness of 26 μm was obtained using a thermal mechanical analyzer (TM-9400) and a humidity atmosphere adjustment device (HC-1) manufactured by ULVAC-RIKO Inc. Measures the elongation when the humidity is changed from 30% RH to 70% RH at 23 ° C. and a load of 5 g, and determines the hygroscopic expansion coefficient of the polyesterimide film as the average elongation value of the film at 30% RH to 70% RH. It was.

<Flame retardance>
Forty test pieces of polyesterimide film having a thickness of 12 μm were prepared so as to be 20 cm long × 5 cm wide. Of the 40 test pieces, 20 pieces were left in an atmosphere of 23 ° C. and 50% relative humidity for 48 hours or longer (acceptance state), and the remaining 20 pieces were aged at 70 ° C. for 168 hours, then at 23 ° C. and relative humidity. It cooled in the desiccator below 20% for 4 hours. VTM-0 evaluation was performed by a flammability test in an atmosphere of 23 ° C. and a relative humidity of 55% using an evaluation method based on the UL94VTM test, using each of five polyesterimide films. (The flame used for evaluation at this time was a blue flame having a size of 20 mm, and the temperature rise time of copper slag from 100 ° C. to 700 ° C. was 42.9 seconds.)

<Solder heat resistance evaluation>
Cut the copper foil / polyesterimide laminate to a size of 3 cm in length x 3 cm in width, mask the 2.5 cm x 2.5 cm center using a masking tape, under the same conditions as above, The copper foil was etched using a ferric chloride solution (Tsurumi Soda Co., Ltd., 40 Baume, ferric chloride 37% or more) to obtain a test piece. The obtained test piece was allowed to stand for 1 hour or longer in a dryer 105 ° C. and dried, and then left in the solder bath surface set at 300 ° C. for 2 minutes so that the copper foil side was in contact with the copper. The appearance of the foil and the polyesterimide film, such as blistering and wrinkle generation, was evaluated by visual observation, and a case where no change in the appearance was observed was taken as a good result (◯).

<Boiled solder heat resistance evaluation>
The test piece produced similarly to solder heat resistance evaluation was obtained, purified water was put into the container with a reflux condenser, the obtained test piece was immersed, and it left still at 100 degreeC for 2 hours. Then, the test piece was thrown into normal temperature purified water, each test piece was taken out one by one, and the water | moisture content of both surfaces was wiped off with the paper towel. Then, in a solder bath set at 280 ° C., leave it on the solder bath surface for 2 minutes so that the copper foil side is in contact, and visually check the appearance of the copper foil and the polyesterimide film, such as blisters and wrinkles. A case where no change in appearance was observed was evaluated as a good result (◯).

<Adhesive strength between copper foil and polyesterimide layer>
About the measuring method of the test piece, it carried out according to JIS C6471 standard. For the test piece, a copper foil / polyesterimide laminate was cut into a size of 15 cm long × 1 cm wide, masked with a 1 cm center width of 3 mm using a masking tape, and chlorinated under the same conditions as above. The copper foil was etched using a ferric solution. The obtained test piece was left to dry at 105 ° C. for 1 hour or longer and then attached to a FR-4 substrate having a thickness of 3 mm with a double-sided adhesive tape. A conductor having a width of 3 mm was peeled off at the interface with the polyesterimide film and attached to an aluminum tape as a grip allowance to prepare a sample.

  The obtained sample was fixed to a tensile tester (Autograph AG-10KNI) manufactured by Shimadzu Corporation. When fixing, a jig was attached to surely peel off in the direction of 90 °, and the load at the time of peeling 50 mm at a speed of about 50 mm / min was measured and calculated as the adhesive strength per 1 cm.

<Elastic modulus>
Using a RTG-1210 type tensile tester manufactured by Orientec Co., Ltd., a polyimide film of 3 mm × 50 mm was stretched at a test length of 50 mm and a test speed of 50 mm / min, and the elastic modulus was a tensile elongation of 0.4% of the polyesterimide film. It was calculated from the slope of the stress between ˜1.0%. (When a 50 mm sample breaks when it is stretched to 100 mm, it is described as “tensile elongation at break of 100%”.)

<Trouser tear strength>
A polyester imide film is cut into 50 mm × 150 mm as a sample, and an RTG-1210 type tensile test device (equipped with UR-50N-D type load cell made by Orientec Co., Ltd.) is used, and the method described in JIS K7128-1. Measured at a test speed of 50 mm / min.

<Warpage>
A copper foil / polyesterimide laminate was cut to a size of 10 cm × 10 cm and left in a constant temperature and humidity chamber at 23 ° C. and 50% humidity for one day. Then, using a ruler, the distance between each of the four pieces of the sample and the installation surface was measured, and the average value of the measured distances was taken as the value of warpage. Here, the case of curling to the polyesterimide side was defined as the value (+).

<Melting heat peak temperature (a) ° C., temperature range ΔT = ((b) − (a)) ° C.>
About 5 mg of tetracarboxylic dianhydride (hereinafter referred to as TABP) having an ester structure represented by the formula (15) was weighed, put in an attached aluminum sample container, covered with a lid, and crimped to prepare a measurement sample. Similarly, an unbalanced aluminum sample container and a lid crimped were used as standard substances. A standard material and a measurement sample are placed in a heating furnace of a differential scanning calorimeter (DSC-60, manufactured by Shimadzu Corporation), and the measurement is performed at a heating rate of 10 ° C./min in an N ₂ atmosphere at a room temperature to 350 ° C. Measurements were made in the range. The peak temperature of the heat of fusion is (a) ° C., and the temperature that is the intersection of the virtual tangent with the contact temperature being the temperature at which the rise to the heat of fusion peak starts, and the straight line along the substantially linear portion of the heat of fusion peak is (b) The temperature range ΔT = ((b) − (a)) ° C. was calculated. The calibration of temperature and heat flow was performed with an indium standard material.

Example 1
<Polymerization of polyesterimide precursor, imidization and polyesterimide film property evaluation>
In a 300 ml flask, 10 g of TABP was placed in 150 ml of γ-butyrolactone solution, heated to 200 ° C. in an oil bath and dissolved with stirring over 30 minutes. At this time, no insoluble matter was observed. Thereafter, heating and stirring of the oil bath were stopped and the mixture was gradually cooled to room temperature. By allowing the solution to stand at room temperature, acicular yellowish white crystals were precipitated while the solution was slowly separated into two layers. The precipitate was collected by filtration, heated and dried at 130 ° C. for 2 hours at a heating rate of 10 ° C./min while reducing the pressure in a vacuum dryer, and then further heated at 200 ° C. at a heating rate of 10 ° C./min. After heating and drying for a period of time and cooling to room temperature while maintaining the degree of vacuum, the pressure was changed to atmospheric pressure, and then high purity TABP yellow crystals of the target product were obtained.

  As a result of measuring 5 mg of the obtained TABP with a differential scanning calorimeter (DSC-60, manufactured by Shimadzu Corporation), the peak temperature of the heat of fusion (a) is 325 ° C., and the temperature range ΔT = ((b) − (a )) = 3.2 ° C.

6.42 mmol of a diamine having an ester structure represented by the formula (17) (hereinafter referred to as BPIP) and a diamine having an ester structure represented by the formula (21) (hereinafter referred to as APAB) in a well-dried sealed reaction vessel with a stirrer. 6.42 mmol was added, 61 mL of N-methyl-2-pyrrolidone was added, and the solution was heated to 80 ° C. to dissolve. After dissolution, 13.38 mmol of TABP powder obtained above was gradually added to this solution. By stirring for 30 minutes, the solution viscosity increased rapidly. The mixture is further stirred for 4 hours, has a repeating unit represented by the general formula (1) and a repeating unit represented by the formula (2), and the molar ratio of the formula (1) and the formula (2) is the formula (1). A transparent, uniform and viscous polyesterimide precursor solution having a ratio of / formula (2) = 50/50 was obtained. Here, in Formula (2), B is a divalent aromatic group represented by Formula (7).

  Even if this polyesterimide precursor solution was allowed to stand at room temperature and 20 ° C. for one month, no precipitation or gelation occurred, and the solution storage stability was high.

  A 12 μm-thick copper foil (NIPPON ELECTRIC CO., LTD. USLP foil) was placed on a metal coating table so that the matte surface was the surface. The surface temperature of the coating table was set to 90 ° C., and the polyesterimide precursor solution was applied to the copper foil mat surface with a doctor blade. Then, after leaving still for 30 minutes on a coating table, and further leaving still in a dryer at 100 ° C. for 30 minutes, a laminate of a copper foil / polyesterimide precursor without tackiness (the thickness of the polyesterimide precursor layer is 47 μm and 24 μm) was obtained. Next, the laminate of the copper foil / polyesterimide precursor was fixed with a tape on a SUS metal plate, and 30 ° C. at 150 ° C. at a temperature rising rate of 5 ° C./min in a hot air drier in a nitrogen atmosphere. Minutes, imidization was carried out at 200 ° C. for 1 hour and at 400 ° C. for 1 hour. Thereafter, the SUS metal plate was removed, and a copper foil / polyesterimide laminate without curling was obtained. Etching the copper foil of this copper foil / polyesterimide laminate with aqueous ferric chloride (Tsurumi Soda Co., Ltd., 40 Baume, ferric chloride 37% or more) at room temperature or under 50 ° C heating conditions By doing so, the light brown polyesterimide film with a film thickness of 26 micrometers and 12 micrometers was obtained.

  This 26 μm thick polyesterimide film was not broken by the 180 ° bending test and showed flexibility. It was not soluble in organic solvents such as N-methyl-2-pyrrolidone and dimethylacetamide. Further, TMA measurement showed a low linear thermal expansion coefficient equivalent to 22 ppm / ° C. (average value between 50 ° C. and 200 ° C.) and copper foil, and the warpage was 1 mm. When the hygroscopic expansion coefficient was measured, it was 4.2 ppm /% RH (an average value between 30% RH and 70% RH) and an extremely low hygroscopic expansion coefficient. When the flame retardancy of the polyesterimide film having a thickness of 12 μm was evaluated, the performance of UL94VTM-0 was shown. Moreover, it showed good solder heat resistance and boiling solder heat resistance. The elastic modulus was as low as 5.9 GPa, and the trouser tear strength was high tear strength of 85 mN in a 26 μm polyesterimide film. Further, the warpage was a good value of 1 mm.

(Example 2)
BPIP 8.99 mmol and APAB 3.85 mmol were placed in a well-closed sealed reaction vessel with a stirrer, N-methyl-2-pyrrolidone 63 mL was added, and the solution was heated to 80 ° C. to dissolve. After dissolution, 13.38 mmol of TABP was gradually added to this solution. By stirring for 30 minutes, the solution viscosity increased rapidly. The mixture is further stirred for 4 hours, has a repeating unit represented by the general formula (1) and a repeating unit represented by the formula (2), and the molar ratio of the formula (1) and the formula (2) is the formula (1). A transparent, uniform and viscous polyesterimide precursor solution having a ratio of / formula (2) = 70/30 was obtained. Here, in Formula (2), B is a divalent aromatic group represented by Formula (7).

  According to the method described in Example 1, film formation and imidization were performed to produce a polyesterimide film, and physical properties were similarly evaluated. The physical property values are shown in Table 1. In addition to the results shown in Table 1, the warpage was as good as 10 mm.

(Example 3)
In a well-dried sealed reaction vessel with a stirrer, BPIP 6.88 mmol, diamine having an amide structure represented by the formula (22) (hereinafter referred to as DABA) 6.88 mmol were placed, N-methyl-2-pyrrolidone 65 mL was added, and the solution Was dissolved by heating to 80 ° C. After dissolution, 14.33 mmol of TABP powder obtained in Example 1 was gradually added to this solution. By stirring for 30 minutes, the solution viscosity increased rapidly. The mixture is further stirred for 4 hours, has a repeating unit represented by the general formula (1) and a repeating unit represented by the general formula (2), and the molar ratio of the formula (1) and the formula (2) is the formula (1). ) / Formula (2) = 50/50, a transparent, uniform and viscous polyesterimide precursor solution was obtained. Here, in Formula (2), B is a divalent aromatic group represented by Formula (8).

According to the method described in Example 1, film formation and imidization were performed to produce a polyesterimide film, and physical properties were similarly evaluated. The physical property values are shown in Table 1. In addition to those shown in Table 1, the warpage was also a good value of 1 mm.

Example 4
In a well-dried closed reaction vessel with a stirrer, BPIP 9.63 mmol, diamine having an ester structure represented by the formula (23) (hereinafter referred to as BPTP) 4.13 mmol were added, N-methyl-2-pyrrolidone 71 mL was added, and the solution Was dissolved by heating to 80 ° C. After dissolution, 14.79 mmol of TABP powder obtained in Example 1 was gradually added to this solution. By stirring for 30 minutes, the solution viscosity increased rapidly. The mixture is further stirred for 4 hours, has a repeating unit represented by the general formula (1) and a repeating unit represented by the formula (2), and the molar ratio of the formula (1) and the formula (2) is the formula (1). A transparent, uniform and viscous polyesterimide precursor solution having a ratio of / formula (2) = 70/30 was obtained. Here, in Formula (2), B is a divalent aromatic group represented by Formula (9).

According to the method described in Example 1, film formation and imidization were performed to produce a polyesterimide film, and physical properties were similarly evaluated. The physical property values are shown in Table 1. In addition to those shown in Table 1, the warpage also showed a good value of -3 mm. Here, −3 mm means warping to the copper foil side.

(Comparative Example 1)
9.27 mmol of BPIP was placed in a well-dried sealed reaction vessel with a stirrer, 48 mL of N-methyl-2-pyrrolidone was added, and the solution was heated to 80 ° C. to dissolve. After dissolution, 9.66 mmol of a tetracarboxylic dianhydride (hereinafter referred to as TAHQ) powder having an ester structure represented by the formula (10) was gradually added to this solution. By stirring for 30 minutes, the solution viscosity increased rapidly. The mixture was further stirred for 4 hours to obtain a transparent, uniform and viscous polyesterimide precursor solution.

According to the method described in Example 1, film formation and imidization were performed to produce a polyesterimide film, and physical properties were similarly evaluated. The physical property values are shown in Table 1.

  It showed linear thermal expansion coefficient close to copper foil, high thermal stability and flexibility, low elastic modulus, and relatively high adhesiveness, but the hygroscopic expansion coefficient was relatively high at 7.6 ppm /% RH, and the tear strength Is as low as 42 mN in a 26 μm polyesterimide film. Moreover, the flame retardance performance was low with a film having a thickness of 12 μm, and the performance of UL94VTM-0 was not obtained.

(Comparative Example 2)
According to the method described in Example 1, except that TAHQ was used instead of TABP and APAB 10.49 mol and 4,4′-diaminodiphenyl ether (hereinafter referred to as ODA) 2.62 mol were used as the diamine in Example 1. The imide precursor was polymerized, formed into a film and imidized to produce a polyesterimide film, and the physical properties were similarly evaluated. The physical property values are shown in Table 1. Although it showed linear thermal expansion coefficient close to copper foil, high thermal stability and flexibility, the hygroscopic expansion coefficient was relatively high at 8.3 ppm /% RH, the elastic modulus was high at 7.9 GPa, and the adhesive strength Is as low as 0.3 N / mm, and the tear strength is as low as 42 mN in a 26 μm polyesterimide film. Moreover, the flame retardance performance was low with a film having a thickness of 12 μm, and the performance of UL94VTM-0 was not obtained.

(Comparative Example 3)
In Comparative Example 1, a polyesterimide precursor was polymerized according to the method described in Comparative Example 1 except that a diamine represented by formula (13) (hereinafter referred to as BAPB) was used as the diamine. A polyesterimide film was prepared and similarly evaluated for physical properties. The physical property values are shown in Table 1.

  High glass transition temperature, high adhesiveness, and elastic modulus showed a low value of 5.2 GPa, but the linear thermal expansion coefficient showed a high value of 32 ppm / ° C., and the hygroscopic expansion coefficient was as high as 13.2 ppm /% RH. The tear strength is as low as 45 mN in a 26 μm polyesterimide film. In addition, blistering was observed in the solder heat resistance test, and the flame resistance performance was low with a film having a thickness of 12 μm, and the performance of UL94VTM-0 was not obtained.

(Comparative Example 4)
In Comparative Example 1, except that TABP was used in place of TAHQ and APAB was used as the diamine, a polyesterimide precursor was polymerized according to the method described in Comparative Example 1 to form a polyesterimide film by film formation and imidization. In the same manner, physical properties were evaluated. The physical property values are shown in Table 1. Evaluation of flame retardancy of polyimide film with high thermal stability and flexibility, low hygroscopic expansion coefficient, high tear strength and film thickness of 12 μm showed the performance of UL94VTM-0, but the linear thermal expansion coefficient was 13 ppm. The coefficient of linear thermal expansion was lower than that of copper foil at / ° C., the adhesive strength was as low as 0.4 N / mm, and the elastic modulus was as high as 7.7 GPa.

  Thus, the polyesterimide precursor of the present invention has repeating units represented by the above formulas (1) and (2), and the molar ratio of the formulas (1) and (2) is the formula (1). / Equation (2) = 20/80 to 80/20, so high flame retardancy, low hygroscopic expansion coefficient, low linear thermal expansion coefficient, high glass transition temperature, low elastic modulus, and high tear strength A polyesterimide having both can be provided.

  The polyesterimide of the present invention can be suitably used as an electrical insulating film, a flexible printed wiring board, a display substrate, an electronic paper substrate, a solar cell substrate, particularly a flexible printed wiring board substrate in various electronic devices.

Claims (9)

It has a repeating unit represented by the following formula (1) and formula (2), and the molar ratio of formula (1) and formula (2) is formula (1) / formula (2) = 20/80 to 80/20. A polyesterimide precursor, characterized in that

(In Formula (1) and Formula (2), Ar is a tetravalent aromatic group represented by Formula (3). In Formula (2), B represents at least one of Formulas (4) to (8)). It is a divalent aromatic group selected from one, R _{1 to} R ₉ represent an alkyl group having 1 to 6 carbon atoms and a hydrogen atom, and are independent and may be the same or different. .)

The polyesterimide precursor according to claim 1, wherein B is a repeating unit represented by formula (7), formula (8), or formula (9) in formula (2). precursor.

  The polyesterimide precursor according to claim 1, wherein B is a repeating unit represented by the formula (7) in the formula (2).   The weight average molecular weight Mw is 30,000 or more and 400,000 or less, The polyesterimide precursor in any one of Claims 1-3 characterized by the above-mentioned.   A polyesterimide obtained by imidizing the polyesterimide precursor according to any one of claims 1 to 4.   A method for producing a polyesterimide, wherein the polyesterimide precursor according to any one of claims 1 to 4 is obtained by heating or imidization using a dehydrating reagent.   A laminate comprising a polyesterimide layer and a metal layer, wherein the polyesterimide layer is composed of the polyesterimide according to claim 5.   The polyesterimide precursor according to any one of claims 1 to 4 is coated on a metal foil, dried, and then imidized by heating or using a dehydrating reagent. The laminated board as described in.   The flexible printed wiring board characterized by the metal layer of the laminated board in any one of Claim 7 and Claim 8 being patterned by wiring.